Anthocyanins are natural pigments with antioxidant effects that exist in various fruits and vegetables. The accumulation of anthocyanins is induced by environmental signals and regulated by transcription factors in plants. Numerous evidence has indicated that among the environmental factors, light is one of the most signal regulatory factors involved in the anthocyanin biosynthesis pathway. However, the signal transduction of light and molecular regulation of anthocyanin synthesis remains to be explored. Here, we focus on the research progress of signal transduction factors for positive and negative regulation in light-dependent and light-independent anthocyanin biosynthesis. In particular, we will discuss light-induced regulatory pathways and related specific regulators of anthocyanin biosynthesis in plants. In addition, an integrated regulatory network of anthocyanin biosynthesis controlled by transcription factors is discussed based on the significant progress.

Plants have evolved complicated defense and adaptive systems to grow in various abiotic stress environments such as drought, cold, and salinity. Anthocyanins belong to the secondary metabolites of flavonoids with strong antioxidant activity in response to various abiotic stress and enhance stress tolerance. Anthocyanin accumulation often accompanies the resistance to abiotic stress in plants to scavenge reactive oxygen species (ROS). Recent research evidence showed that many regulatory pathways such as osmoregulation, antioxidant response, plant hormone response, photosynthesis, and respiration regulation are involved in plant adaption to stress. However, the molecular regulatory mechanisms involved in controlling anthocyanin biosynthesis in relation to abiotic stress response have remained obscure. Here, we summarize the current research progress of specific regulators including small RNAs, and lncRNAs involved in the molecular regulation of abiotic stress-induced anthocyanin biosynthesis. In addition, an integrated regulatory network of anthocyanin biosynthesis controlled by microRNAs (miRNAs), long non-coding RNAs (lncRNAs), transcription factors, and stress response factors is also discussed. Understanding molecular mechanisms of anthocyanin biosynthesis for ROS scavenging in various abiotic stress responses will benefit us for resistance breeding in crop plants.

Armadillo (ARM) was a gene family important to plants, with crucial roles in regulating plant growth, development, and stress responses. However, the properties and functions of ARM family members in maize had received limited attention. Therefore, this study employed bioinformatics methods to analyze the structure and evolution of ARM-repeat protein family members in maize. The maize (Zea mays L.) genome contains 56 ARM genes distributed over 10 chromosomes, and collinearity analysis indicated 12 pairs of linkage between them. Analysis of the physicochemical properties of ARM proteins showed that most of these proteins were acidic and hydrophilic. According to the number and evolutionary analysis of the ARM genes, the ARM genes in maize can be divided into eight subgroups, and the gene structure and conserved motifs showed similar compositions in each group. The findings shed light on the significant roles of 56 ZmARM domain genes in development and abiotic stress, particularly drought stress. RNA-Seq and qRT-PCR analysis revealed that drought stress exerts an influence on specific members of the ZmARM family, such as ZmARM4, ZmARM12, ZmARM34 and ZmARM36. The comprehensive profiling of these genes in the whole genome, combined with expression analysis, establishes a foundation for further exploration of plant gene function in the context of abiotic stress and reproductive development.

Background: Maize (Zea mays L.) is one of the main agricultural crops with the largest yield and acreage worldwide. Maize at the germination and sprouting stages are highly sensitive to low-temperatures, especially in high-latitude and high-altitude regions. Low-temperature damage in early spring presents a major meteorological disaster in maize, severely affecting plant growth and maize yield. Therefore, mining genes tolerant to low temperatures is crucial. We aimed to analyze differential gene expression and construct co-expression networks in maize under low temperatures. Methods: Inbred lines, Zhongxi 091/O2 and Chang 7-2, are tolerant and sensitive to low temperatures at the germination and sprouting stages, respectively. We grew these lines at 10 °C and 2 °C at the germination and sprouting stages, respectively. Samples were taken at five time points (0, 6, 12, 24, and 36 h) during the two stages, and transcriptome sequencing was performed. The analyses were conducted using weighted gene co-expression networks analysis (WGCNA), Gene Ontology (GO), the Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene co-expression networks. Results: WGCNA was used to construct co-expression networks at two stages, resulting in six and nine co-expression modules, respectively. Two modules at the germination stage (blue and yellow) and two modules at the sprouting stage (turquoise and magenta) were identified. These were significantly associated (p < 0.01) with tolerance at low temperature. The differentially expressed genes (DEGs) in the four modules revealed entries related to hormone and oxygen-containing compound responses by GO functional enrichment. Among the four modules, DEGs from three modules were all significantly enriched in the MAPK signaling pathway. Based on the connectivity, the top 50 genes for each module were selected to construct a protein interaction network. Seven genes have been proven to be involved in the response to low-temperature stress. Conclusion: WGCNA revealed the differences in the response patterns of genes to low-temperature stress between tolerant and sensitive lines at different time points. Seven genes involved in low-temperature stress were functionally annotated. This finding suggests that WGCNA is a viable approach for gene mining. The current findings provide experimental support for further investigation of the molecular mechanisms underlying tolerance to low temperatures in maize.